Justice Department has opened a critical incident review into law enforcement’s response to the deadly mass shooting at Robb Elementary School in Uvalde, Texas.

The inquiry comes at the request of Uvalde Mayor Don McLaughlin after reports indicate that law enforcement waited during crucial minutes before taking out the 18-year-old gunman who killed 19 children and two teachers while barricaded in a classroom Tuesday.

“The goal of the review is to provide an independent account of law enforcement actions and responses that day, and to identify lessons learned and best practices to help first responders prepare for and respond to active shooter events,” the department said in a statement Sunday.

The Justice Department will publish a report with its findings at the conclusion of its review, the statement noted.